Powering Signals When Using Peco Spring Loaded Turnouts

[ATLANTIC CENTRAL]

Rich, do you have any diodes in these LED circuits?

It seems to me that this might simply be the bipolar LED not liking the DCC signal on the one color? 

LED's are after all, DC devices. The DCC signal is not really DC.

The thing that concerns me about this is voltage drop?

Sheldon

[richhotrain]

ATLANTIC CENTRAL

Rich, do you have any diodes in these LED circuits?

It seems to me that this might simply be the bipolar LED not liking the DCC signal on the one color? 

LED's are after all, DC devices. The DCC signal is not really DC.

The thing that concerns me about this is voltage drop?

Sheldon 

No, I do not have any diodes in the signal wiring, but I wonder if diodes are the solution to the bi-polar LED wiring. I wish that I understood more about such wiring.

When you say that you are concerned about voltage drop, are you saying that powering the LEDs off the rails may pull too much power from locomotive performance?

Rich

[gregc]

richhotrain

But when I do that with the search light signal, the bi-polar LED turns amber on one of the routes.

isn't this a good thing?

should the signal be clear if the turnout is routed straight, and indicate a lessed indication if switched to the diverging route?

and shouldn't the signal toward the turnout on the diverging route be either stop or approach (yellow)?

[richhotrain]

gregc

 

richhotrain

But when I do that with the search light signal, the bi-polar LED turns amber on one of the routes. 

isn't this a good thing?

should the signal be clear if the turnout is routed straight, and indicate a lessed indication if switched to the diverging route?

and shouldn't the signal toward the turnout on the diverging route be either stop or approach (yellow)? 

Not a good thing. What is happening is that instead of turning from red to green, it is trying to show both colors and it turns out an orangey color which is why I referred to it as amber. I need a way to block the green LED when the red LED is activated. The search light signal is a bi-polar red/green LED, no yellow.

Rich

[ATLANTIC CENTRAL]

richhotrain

 

 

ATLANTIC CENTRAL

Rich, do you have any diodes in these LED circuits?

It seems to me that this might simply be the bipolar LED not liking the DCC signal on the one color? 

LED's are after all, DC devices. The DCC signal is not really DC.

The thing that concerns me about this is voltage drop?

Sheldon 

 

 

 

No, I do not have any diodes in the signal wiring, but I wonder if diodes are the solution to the bi-polar LED wiring. I wish that I understood more about such wiring.

 

When you say that you are concerned about voltage drop, are you saying that powering the LEDs off the rails may pull too much power from locomotive performance?

Rich

 

Yes

[richhotrain]

OK, I found the solution to the bi-polar LED issue.

By placing a diode in line with the Green LED wire, I can prevent a current backflow that was turning the red/green LED to an orange blended color. 

Now, my only concern is bleeding off too much DCC power by wiring the signals to the DCC-powered rails. I do have a RRampMeter hooked up to the layout, so later today I will check the effect of voltage drop. One or two signal hookups should not matter, but I have a considerable number of signals to wire up, so voltage drop may be a serious issue.  Any thoughts?

[richhotrain]

I just tested with my RRampMeter. Each signal draws 0.01 amp. That would mean that it would take 100 signals, more than double what I need, to consume 1 amp of DCC power. Wouldn't that be acceptable?

Rich

[gregc]

i think so

[RR_Mel]

richhotrain

I just tested with my RRampMeter. Each signal draws 0.01 amp. That would mean that it would take 100 signals, more than double what I need, to consume 1 amp of DCC power. Wouldn't that be acceptable?

Rich

 

Rich

 

10ma on LEDs is a bit too bright for me, I would add some resistance to drop it to 5ma.  That would drop your total current from 1 amp to a ½ amp.

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[hon30critter]

RR_Mel

Rich   10ma on LEDs is a bit too bright for me, I would add some resistance to drop it to 5ma.  That would drop your total current from 1 amp to a ½ amp.     Mel

Hi Rich,

I agree with Mel. Increasing the value of the resitors will not only save you some power, but you may also find that the brightness of the LEDs is toned down to the point where they don't burn your eyes if you look straight at them. I have seen some signal systems where the LEDs were so bright they were almost blinding.

Dave

[RR_Mel]

I run my three color LEDs at;

 

Red 2ma

Yellow 11ma

Green 4ma

 

At those current levels they look pretty close to me in brightness.  Easily seen at full room brightness and not to bright for my moonlight scenes.

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[hon30critter]

RR_Mel

I run my three color LEDs at;   Red 2ma Yellow 11ma Green 4ma

Hi Mel,

I'm working on tri-colour signals for a friend. I've only worked with tri-colour LEDs once before and those were for classification lights so having them bright wasn't too much of an issue. I'm curious to know what value resistors you are using.

Thanks,

Dave

[RR_Mel]

Dave

 

My 82 yr old brain isn’t doing much today.  I had to go to my MEGA and look at the resistors.

 

I’m driving my LEDs (SMTL4-RGY) from the Arduino MEGA 5 volt power supply.

 

The red is 1KΩ = 2ma @ 5 volts

The green is 560Ω = 4 ma @ 5 volts

The yellow is 180Ω =11ma @ 5 volts

 

Voltage makes a huge difference in the current draw of a LED, at 10 volts double the size of the resistors and at 15 volt triple the values.

 

I really like the SMTL4-RGY LEDs they work better than GREAT.

 

 

 

It was amazingly easy to solder the tiny #36 Litz wires to them.  I put a rubber band around the handles of my needle nose pliers to hold the tiny LED then put the pliers in my Panavise. A small dob of soldering paste and a quick touch with my soldering iron and it was done.

 

I couldn’t have done it before my cataract surgery, the LED is less than 3mm at its widest point.  

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[rrinker]

 You have better vision than I do, at better than 30 years older than me. No way can I do those super fine wires on SMD devices. And unfortunately nothing can fix that, I'm for the most part only seeing out of one eye, so it's not just the sharpness, my depth perception is off.

 Are those the RGY LEDs from RR-CirKits? The ones he sells have a perfect aqua green for railroad signals - the typical green LED is WAY off. You might not notice it until you see what one of the nice ones looks likes.

 

                                              --Randy

 

[RR_Mel]

rrinker

 You have better vision than I do, at better than 30 years older than me. No way can I do those super fine wires on SMD devices. And unfortunately nothing can fix that, I'm for the most part only seeing out of one eye, so it's not just the sharpness, my depth perception is off.

 Are those the RGY LEDs from RR-CirKits? The ones he sells have a perfect aqua green for railroad signals - the typical green LED is WAY off. You might not notice it until you see what one of the nice ones looks likes.

 

                                              --Randy

 

 

 

Randy

 

The LEDs I went with are SMTL4-RGY from Bivar.

 

https://www.bivar.com/Files/Datasheets/SMTL4-RGY.pdf

 

I bought mine from Mouser, best price.  25 LEDs for $31 delivered.  They are available from most large electronic stores.

 

While attempting to solder the first one I went with a surgical clamp to hold it, shortly after clamping it and putting the clamp in my Panavise the LED crumbled, 24 left.

 

I went with my Craftsman 6” needle nose pliers with a rubber band around the handles then put the pliers in the Panavise.  That worked on the following 24.

 

While testing one the red wire inadvertently bypassed the resistor, I heard the pop, 23 left.

 

The SMTL4-RGY is flat with no lens, while attempting to attach a 3mm lens off a clear bright white LED the lens slipped when gluing the lens to the LED.  Attempting to align the lens I cracked the LED 22 left.

 

The next 22 went well.  I successfully installed all 22 of them into my Mel made signal heads.  I only need 18 heads, having several spares is good.

 

 

I’m quite happy with the operation of the signal heads and to me the LED colors are very nice, to me the three colors are perfect. 

 

As far as I’m concerned the SMTL4-RGY are perfect and the price is right.

 

If I can just get my Arthritis to cooperate I should have all 18 signals in and working off my Mel MEGA processor before Thanksgiving.

 

I’ve had a really bad right knee for years and today I received a custom made knee brace and I’m finally able to walk without pain.  That should speed up the process of working on my layout.

 

For anyone interested I have a post on my blog started and I add to it as the construction process continues.

 

 

https://melvineperry.blogspot.com/p/blog-page_49.html

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[hon30critter]

RR_Mel

The LEDs I went with are SMTL4-RGY from Bivar.

Hi Mel,

Thanks for the resistor values.

Do you have a picture of the green indication? The LEDs that I am using for the club's signals are about $4.00/100. The Canadian price for 100 of the LEDs that you are suggesting is $155.00 incl. tax and shipping. I'm not happy with the green tone on the cheap LEDs but I'm reluctant to spend that much money unless the green is hugely superior.

Dave

[richhotrain]

All of this talk about about milliamps prompts me to ask, how do you determine the amount of milliamps on an LED. I have seen various reports stating LED current draws to be 20 to 30 ma without a resistor attached. Is there a way to measure exact milliamps for a specific LED?

Rich

[gregc]

with a light meter.

20ma is typically the max.   But over the years, LED optical intensity has increased.    The value for different color LED and manufactures may be different.

[richhotrain]

gregc

with a light meter.

20ma is typically the max.   But over the years, LED optical intensity has increased.    The value for different color LED and manufactures may be different. 

Thanks, greg. It does seem that 20 ma is the standard, so I will move forward on that assumption.

Rich

[RR_Mel]

Dave

 

I’m not very good taking pictures but I tried on the SMTL4-RGY

 

 

 

 

I had used three wire bi-color LEDs for my first signaling system about 20 years ago and they worked out great. When I was in the designing and planning portion of my current project I wanted to go with common Anode.  I also used the brass tube of the signals as common, I never liked the idea of having an “electrically hot” pole that close to the tacks.

 

I tried several batches of the newer three wire bi-color LEDs in both common anode and cathode all had unusable yellow color and pitiful at best green.  I went into search mode for months and finally ask on the Forum.  Randy suggested a three color LED from a hobby dealer and Like you I found it way too pricy for my budget, back to search mode.

 

I finally found the SMTL4-RGY and was a bit leery about soldering wires to such a tiny object.  I finally decided to give it a shot and ordered 25.  The rest is history, they work better that GREAT and soldering the #36 Litz wires to it was super easy once I got the hang of it.

 

Going to the #36 Litz wire made it possible to easily get four (or more) wires down the 1/16" bras tube/mast.

 

Rich

 

All the LED specs I’ve seen say 20 ma max, I can actually hear they’re tiny pop.  I never run a LED at max current, way too bright, headlights at about 10ma, passenger car lighting 2ma to 4ma, my signals 2ma to 10ma.

 

I’ve gotten lazy over the years and ended up using a Googled calculator to figure out the resistance needed to obtain the exact resistance, you enter the voltage and current needed and it gives you the resistance.

 

I don’t have any affiliation with Stan Silvermen or Stans Trains but he has a calculator program available for figuring out all most anything about Model Railroading.  You name it and it’s available with a simple click.  I’ve been using it for many years and it spoiled me, I rarely use my TI-30 any more.

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[ATLANTIC CENTRAL]

Glad it appears we have found Rich a solution. Some interesting info here.

I use LED signals but decided against targets in favor of D type three lamp and two lamp color light heads.

And my wiring is done to allow LED's or 12v lamps.

Sheldon 

[rrinker]

 Yeah, these 3 in one LEDs wouldn't work for me anyway, nearly all of my signals need to be 3 light Type G signals. There are single green LEDs with the right color frequency to equal the more aquamarine of railroad signals. If you ever get to see the inner workings of a signal, take a look at the 'green' filter - very definitely bluish green, not a bright grass green.

On LED current - 20ma is a MAXIMUM. LEDs do not work on voltage like a filament bulb does, they work on current. Otherwise the same things apply. A filament bulb will start to glow well below the rated voltage. Exceed the rated vooltage, and the life drops off sharply, excced the rated voltage by enough and the bumb burns out nearly instantly. With an LED, they will light up when sourced with well below their maximum current. Just nooot at maximum brightness. Exceed the rated maximum current, and the lifespan is shortened. Exceed it by a lot, and you create DEDs, dark emitting diodes.

 A filament bulb will take all the voltage you give it, to the point of destructions. But it will consume only a certain amount of current, say it's a 540mA bulb, then it draws 50mA. (clightly complicated by the fact that the filament material has a different resistence depending on if it's hot or if it's cold, but basically it's one current level). An LED will take all the current supplied to it, even to destruction, but it will only ever drop a set voltage, say maybe 2.1 volts for a red LED. Doesn't matter if you allow only 2mA, or 20mA, the voltage across the LED will be 2.1 volts if that's what the specifications say. (subject to the fact that the perfect semiconductor does not exist and the voltage/current graph is not perfectly linear, but the idea is close enough for our purposes).

 The voltage controls the brightness of a filament bulb. The current controls the brightness of an LED> The only thing you can say for sure about what current to use with an LED is to never exceed the maximum. The data sheet might give a chart of current vs light intensity, but without a light meter, those things are almost meaningless. Experimentation is your best bet. The only way someone else's resistor values would also work would be if they are using EXACTLY the same LEDs that you are using, their values will not likely match yours. 

                          --Randy

 

[richhotrain]

richhotrain

All of this talk about about milliamps prompts me to ask, how do you determine the amount of milliamps on an LED. I have seen various reports stating LED current draws to be 20 to 30 ma without a resistor attached. Is there a way to measure exact milliamps for a specific LED?

Rich 

The reason that I asked about the amount of milliamps in an LED is that I wanted to get some idea of the amount of total current drawn through all of my signals if they are powered through the rails on my DCC layout.

So, if I have 50 signals, the unresistored LEDs would consume 1,000 ma, or 1 amp. However, my resistored LEDs (carried over from my prior layout) each only draw 0.01 amp, or 10 ma. So, I assume that the resistors that I am using reduce the current flowing through each LED by 50%, thereby consuming only 1/2 amp in total.

That seems acceptable, but if I want to reduce the total current draw to 1/4 amp, then I need to increase the resistance value of the resistors used by another 50%.

Is all of this correct?

Rich

[rrinker]

The unresistored LEDs would draw whatever power your DCC system can supply - for a nanosecond, as they all instantly flashed into nothing. Then they would draw zero current.

All LEDs MUST have a resistor to limit the current to no more than 20ma. Without a resistor, the LED will draw whatever current the power supply can supply, even if that exceeds the limit and destroys the LED.

The other point everyone is trying to get across is that at 20ma, most LEDs will be far too bright, and you will most definitely want to use a larger resistor, resulting in a lower current. For the LEDs Mel is using, it's truly a miniscule current that results in a brightness he likes. 

Bottom line of it all is - it's not going to matter at all to run LED turnout indicators right from the DCC bus. Unless you are running the whole layuout with one of the really low power starter systems. But a 5 amp system or more - the LEDs will be negligible. It's like having resistor wheels on cars for detection. It's a resistor right across the rails, so it draws current from the system. My cars have 5K per car. It would take 1000 cars to draw 3 amps.

                                  --Randy

[richhotrain]

rrinker

The other point everyone is trying to get across is that at 20ma, most LEDs will be far too bright, and you will most definitely want to use a larger resistor, resulting in a lower current. 

I understood that from the beginning. I was just curious about the unresistorted amount of milliamps in a typical LED.

Rich

[hon30critter]

richhotrain

Is all of this correct?

Yes.

Dave

P.S. That is the shortest answer I have ever given on the forums!!!!

[hon30critter]

RR_Mel

Dave   I’m not very good taking pictures but I tried on the SMTL4-RGY

Hi Mel,

Thanks for taking the time to do that! I like the colours (Randy won't like my spelling of that word!).

I'm going to approach the club to see how much the colour of the green indication matters. One distinct advantage to going with the tri-coloured LEDs is that it gives us the option of setting up a proper signal system down the road. Right now all we want is turnout position indication but that could very well change if we want to install a central control panel and use a proper dispatcher some time down the road.

Thanks again Mel! You (and others) have given the club a lot of support! We are very gratefull for that.

Dave

[RR_Mel]

Dave

 

Randy is correct about the color, it is pure green not the RR signal green but that works for me.

 

The bi-color LEDs are all pitiful, the red and green have hotspots that stick out like a sore thumb and the yellows are red on one side green on the other and not even close to yellow for the yellow in the middle.

 

Incidentally the RR yellow is really more toward amber/yellowish than the SMTL4-RGY.  It is also true yellow.

 

The normal person (not rivet counters) looking at the scale signal heads will not notice the small differences.  Mine look better than great.

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[hon30critter]

RR_Mel

Dave   I’m not very good taking pictures but I tried on the SMTL4-RGY  

Okay Mel, you convinced me to break down and spend the money for the LEDs that you suggested. They were considerably cheaper by the hundred so that's what I bought.

Now I just have to wire the things! I'm going to blame you for my stiff neck!!!

Seriously, thanks for all your help with this!

Cheers!!

Dave

[RR_Mel]

hon30critter

 

 

RR_Mel

Dave   I’m not very good taking pictures but I tried on the SMTL4-RGY  

 

 

Okay Mel, you convinced me to break down and spend the money for the LEDs that you suggested. They were considerably cheaper by the hundred so that's what I bought.

Now I just have to wire the things! I'm going to blame you for my stiff neck!!!

Seriously, thanks for all your help with this!

Cheers!!

Dave

 

I would suggest doing them in small batches of about 20 at a time.  Maybe it’s just me but doing tedious work on tiny stuff plays with my mind as well as my neck and eyes.

 

Forewarned, now you can’t blame me for your stiff neck!

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.